The typical microwave reflector comprises a large metal or fiberglass parabolic surface which may vary in size from several inches to 15 feet or greater in diameter. The reflector typically rests at an angle with respect to the horizontal plane. As a result of this tilt angle, the bottom half of the reflector tends to collect snow, ice or other forms of precipitation, all of which tend to degrade the performance of the reflector.
It is known to attach heating devices to parabolic microwave reflectors in an attempt to remove any ice or snow from the reflector surface. Such heating devices must be suitable for attachment to the curved surface of the parabolic reflector, and must be suitable for heating the relatively large surface of the reflector. Conventional heating methods comprise, for example, using a plurality of heating pad assemblies attached directly to the rear surface of the reflector. Such heating pad assemblies typically comprise a pair of silicone rubber pads between which a heating wire is traversed back and forth to effect heating over substantially the entire area of the pads. A pair of leads extending from the heating pad assembly is connected to a common power source together with leads from several other such heating pad assemblies, there being as many as a dozen or more such heating pad assemblies bonded to the back surface of a microwave reflector.
Employing another heating method, Canadian Patent No. 1,109,913 to Falsetti discloses securing a metal tube, which is heated by a sheathed heating wire, to the metal surface of the microwave reflector. In Falsetti, the microwave reflector is heated by direct metal-to-metal heat conduction. Other methods used to prevent ice or snow buildup on the antenna reflective surface include: (1) using heat tape or other conductive system which is bonded directly to the back side of the antenna, the heat tape having foam insulation applied thereover to reduce heat loss; (2) using radiation systems consisting of a cover of either molded plastic, sewn fabric or plastic which is mechanically attached to the back of the antenna; and (3) using convection systems employing a cover, blower and heater which together form a plenum when attached to the back side of the antenna.
Each of these heating systems entails attaching the heating source to the back side of the antenna. This causes the heating systems to interfere with the antenna support structures located on the back side of the antennas. Another disadvantage with presently available heating systems is that heat loss is very high, even with insulation on the back side and with controllers to activate the heaters only during snow and ice conditions by sensing temperature and precipitation. This results in high operating costs.
Therefore, the object of the present invention is to provide a heating system, and a process for manufacturing the same, in which snow and ice are effectively kept from forming on the reflective surface of the antenna.
It is also an object of the invention to provide a heating system which is not susceptible to the high levels of heat loss, thereby making the system substantially less expensive to operate.
Yet another object of the present invention is to eliminate the requirement of attaching a heating system to the back side of a reflective antenna.